DESCRIPTION: Therapeutic peptides are used to treat human diseases ranging from HIV to diabetes and have some of the best features of small molecule and recombinant protein drugs. Therapeutic peptides account for $13 billion of annual pharmaceutical sales and are part of a growing sector of the biopharmaceutical market. Unfortunately, therapeutic peptides typically suffer from poor stability and short half-lives in the human body, which limits their value. The requirement for high dosing and frequent injections follows, which can be inconvenient, expensive, and dangerous for patients. While there have been methods developed to address these issues, they either: (i) hinge on in vitro or recombinant attachment of a large polymer chain, which dramatically impacts peptide activity or (ii) require in vitro processing steps which increase manufacturing costs and complicate purification. It is now well-established that the stability and half-life of peptide drugs can be greatly improved by conjugation to oligosaccharides that are nonimmunogenic in the human body. Several therapeutic peptides (e.g., Exenatide, Glucagon-like peptide 1) have benefitted significantly from glycosylation with small, human-like glycans by increasing protease resistance, prolonging activity, and improving biodistribution. However, this requires multiple complicated in vitro reactions and purifications which have kept this promising concept from reaching the industrial scale. Glycobia has developed a transformative solution to this growing, unsolved problem by engineering bacteria as a platform for the biosynthesis of therapeutic glycopeptides. These novel strains of Escherichia coli are useful for the expression of recombinant peptides conjugated to nonimmunogenic, human-like oligosaccharides. The hypothesis to be tested here is that non-pathogenic, glycoengineered strains of E. coli can produce affordable recombinant peptide drugs with improved stability, biocompatibility, and prolonged half-life in serum. The main objective of this Phase I project is to identify and characterize peptide drug candidates for animal and preclinical studies in Phase II of this project. This will be accomplished through the following specific aims: (1) express a panel of therapeutic peptide glycoconjugates and screen for expression and glycosylation efficiency; and (2) screen glycoconjugate drug candidates for biophysical properties and in vitro activity. The panel of peptides to be studied here includes seven FDA- approved therapeutic peptides that will be evaluated for expression in the glycoengineered E. coli system. Of these seven peptides, five are currently produced using recombinant expression systems and account for over $2.6 billion in annual sales. Each of the targets will be assayed for solubility, stability, and in vitro activity. This information will be considered along with the commercial potential of each peptide, leading to the identification of candidate peptides for Phase II of this project.